Capacitor for multiple replacement applications

ABSTRACT

An apparatus suitable for use in an air-conditioning system and configured to provide a plurality of selectable capacitance values includes a plurality of capacitive devices and a pressure interrupter cover assembly. Each of the capacitive devices has a first capacitor terminal and a second capacitor terminal. The pressure interrupter cover assembly includes a deformable cover, a set of capacitor cover terminals, a common cover terminal, and a set of insulation structures. The apparatus also includes a conductor configured to electrically connect the second capacitor terminal of at least one of the capacitive devices to the common cover terminal.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation application and claims priority under35 U.S.C. §120 to U.S. application Ser. No. 13/601,205, filed Aug. 31,2012, which is a continuation of U.S. application Ser. No. 12/945,979,filed Nov. 15, 2010, now U.S. Pat. No. 8,270,143 issued on Sep. 18,2012, which is a continuation of U.S. application Ser. No. 12/246,676,filed Oct. 7, 2008, now U.S. Pat. No. 7,835,133 issued on Nov. 16, 2010,which is a continuation application of U.S. application Ser. No.11/733,624, filed Apr. 10, 2007, now U.S. Pat. No. 7,474,519 issued onJan. 6, 2009, which is a continuation application of U.S. applicationSer. No. 11/317,700, filed on Dec. 23, 2005, now U.S. Pat. No. 7,203,053issued on Apr. 10, 2007, which claims benefit to U.S. ProvisionalApplication Ser. No. 60/669,712, filed Apr. 7, 2005.

FIELD OF THE INVENTION

The invention herein relates to a capacitor with multiple capacitorsections selectively connectable to match the capacitance orcapacitances of one or more capacitors being replaced.

BACKGROUND OF THE INVENTION

One common use for capacitors is in connection with the motors ofair-conditioning systems. The systems often employ two capacitors, oneused in association with a compressor motor and another smaller valuecapacitor for use in association with a fan motor. Air-conditioningsystems of different BTU capacity, made by different manufacturers orbeing a different model all may use capacitors having different values.These capacitors have a finite life and sometimes fail, causing thesystem to become inoperative.

A serviceman making a service call usually will not know in advancewhether a replacement capacitor is necessary to repair anair-conditioning system, or what value capacitor or capacitors might beneeded to make the repair. One option is for the serviceman to carry alarge number of capacitors of different values in the service truck, butit is difficult and expensive to maintain such an inventory, especiallybecause there can be a random need for several capacitors of the samevalue on the same day. The other option is for the serviceman to returnto the shop or visit a supplier to pick up a replacement capacitor ofthe required value. This is inefficient as the travel time to pick upparts greatly extends the overall time necessary to complete a repair.This is extremely detrimental if there is a backlog of inoperativeair-conditioning systems on a hot day. This problem presents itself inconnection with air-conditioning systems, but is also found in anysituation where capacitors are used in association with motors and arereplaced on service calls. Other typical examples are refrigeration andheating systems, pumps, and manufacturing systems utilizing compressors.

A desirable replacement capacitor would have the electrical and physicalcharacteristics of the failed capacitor, i.e. it should provide the samecapacitance value or values at the same or higher voltage rating, beconnectable using the same leads and be mountable on the same bracketsor other mounting provision. It should also have the same safetyprotection, as confirmed by independent tests performed by UnderwriterLaboratories or others. Efforts have been made to provide such acapacitor in the past, but they have not resulted in a commerciallyacceptable capacitor adapted for replacing capacitors having a widerange of capacitance values.

My U.S. Pat. No. 3,921,041 and U.S. Pat. No. 4,028,595 disclose dualcapacitor elements in the form of two concentric wound capacitorsections. My U.S. Pat. No. 4,263,638 also shows dual capacitors sectionsformed in a wound capacitive element, and my U.S. Pat. No. 4,352,145shows a wound capacitor with dual elements, but suggests that multipleconcentric capacitive elements may be provided, as does my U.S. Pat. No.4,312,027 and U.S. Pat. No. 5,313,360. None of these patents show acapacitor having electrical and physical characteristics necessary toreplace any one of the variety of failed capacitors that might beencountered on a service call.

An effort to provide a capacitor with multiple, selectable capacitancevalues is described in my U.S. Pat. No. 4,558,394. Three capacitancesections are provided in a wound capacitor element that is encapsulatedin a plastic insulating material. An external terminal lug is connectedwith one of capacitor's sections and a second external terminal lug isprovided with a common connection to all three capacitor sections.Pre-wired fixed jumper leads each connect the three capacitive sectionsin parallel, and the pre-wired fixed jumper leads have a portion exposedabove the plastic encapsulation. This permits one or two jumper leads tobe severed to remove one or two of the capacitor sections from theparallel configuration, and thereby to adjust the effective capacitancevalue across the terminal lugs. The '394 patent suggests that furthercombinations could be made with different connections, but does notprovide any suitable means for doing so.

Another attempt to provide a capacitor wherein the capacitance may beselected on a service call is described in my U.S. Pat. No. 5,138,519.This capacitor has two capacitor sections connected in parallel, and hastwo external terminals for connecting the capacitor into a circuit. Oneof the terminals is rotatable, and one of the capacitor sections isconnected to the rotatable terminal by a wire which may be broken byrotation of the terminal. This provides for selectively removing thatcapacitor section and thereby reducing the capacitance of the unit tothe value of the remaining capacitor. This capacitor provides a choiceof only two capacitance values in a fluid-filled case with a coverincorporating a pressure interrupter system.

In another effort to provide a universal adjustable capacitor for ACapplications, American Radionic Co., Inc. produced a capacitor havingfive concentric capacitor sections in a cylindrical wound capacitorelement. A common lead was provided from one end of the capacitorsections, and individual wire leads were provided from the other ends ofthe respective capacitor sections. The wound capacitor element wasencapsulated in a plastic insulating material with the wire leadsextending outwardly from the encapsulating material. Blade connectorswere mounted at the ends of the wire leads, and sliding rubber bootswere provided to expose the terminals for making connections and forshielding the terminals after connections were made. Various capacitancevalues could be selected by connecting various ones of the capacitorsections in parallel relationship, in series relationship, or incombinations of parallel and series relationships. In a later version,blade terminals were mounted on the encapsulating material. Thesecapacitors did not meet the needs of servicemen. The connections weredifficult to accomplish and the encapsulated structure did not providepressure interrupter protection in case of capacitor failure, whereinthe capacitors did not meet industry safety standards and did notachieve commercial acceptance or success.

Thus, although the desirability of providing a serviceman with acapacitor that is adapted to replace failed capacitors of a variety ofvalues has been recognized for a considerable period of time, acapacitor that meets the serviceman's needs in this regard has notheretofore been achieved. This is a continuing need and a solution wouldbe a considerable advance in the art.

SUMMARY OF THE INVENTION

It is a principal object of the invention herein to provide a capacitorthat is connectable with selectable capacitance values.

It is another object of the invention herein to provide a capacitorincorporating multiple capacitance values that may be connected in thefield to replace the capacitance value or values of a failed capacitor.

It is a further object of the invention herein to provide a capacitorhaving the objectives set forth above and which operates to disconnectitself from an electrical circuit upon a pressure-event failure.

It is also an object of the invention herein to incorporate multiplecapacitance values in a single replacement capacitor that is adapted forconnecting selected ones of the multiple capacitance values into acircuit.

Yet another object of the invention herein to provide a capacitor havingone or more of the foregoing objectives and which provides for safelymaking and maintaining connections thereto.

It is a further object of the invention herein to increase theflexibility of replacing failed capacitors with capacitors incorporatingmultiple capacitance values by utilizing a range of tolerances inselecting the multiple capacitance values provided.

It is another principal object of the invention herein to provide acapacitor for replacing any one of a plurality of failed capacitorshaving different capacitance values and to meet or exceed the ratingsand safety features of the failed capacitor.

In carrying out the invention herein, a replacement capacitor isprovided having a plurality of selectable capacitance values. Acapacitive element has a plurality of capacitor sections, each having acapacitance value. Each capacitor section has a section terminal and thecapacitor sections have a capacitive element common terminal. Thecapacitive element is received in a case together with an insulatingfluid at least partially and preferably substantially surrounding thecapacitive element. The case is provided with a pressure interruptercover assembly, including a cover having a common cover terminal and aplurality of section cover terminals thereon. The section terminals ofthe capacitive element are respectively connected to the section coverterminals and the common terminal of the capacitive element is connectedto the common cover terminal, with the pressure interrupter coverassembly adapted to break one or more connections as required todisconnect the capacitive element from an electrical circuit in theevent that the capacitive element has a catastrophic pressure-eventfailure. The replacement capacitor is connected into an electricalcircuit to replace a failed capacitor by connections to selected ones ofthe common cover terminal and section cover terminals, the capacitorsections and connections being selected to provide one or morecapacitance values corresponding to the capacitor being replaced. Suchconnections may include connecting capacitor sections in parallel,connecting capacitor sections in series, connecting capacitor sectionsin combinations of parallel and series, and connecting one or morecapacitor sections separately to provide two or more independentcapacitance values.

In one preferred aspect of the invention, the capacitive element is awound cylindrical capacitive element having a plurality of concentricwound capacitor sections, each having a capacitance value. The number ofcapacitor sections is preferably six, but may be four or five, or may begreater than six. The capacitor section with the largest capacitancevalue is one of the outer three sections of the capacitive element. Thecapacitor sections are separated by insulation barriers and a metallicspray is applied to the ends of the capacitor sections. The insulationbarriers withstand heat associated with connecting wire conductors tothe capacitor sections.

The case is preferably cylindrical, having a cylindrical side wall, abottom wall and an open top, to accommodate the wound cylindricalcapacitive element.

Also, according to preferred aspects of the invention, the pressureinterrupter cover assembly includes a deformable circular cover having aperipheral edge sealingly secured to the upper end of the case. Thecommon cover terminal and section cover terminals are mounted to thecover at spaced apart locations thereon, and have terminal postsextending downwardly from the cover to a distal end. A rigid disconnectplate is supported under the cover and defines openings therethroughaccommodating the terminal posts and exposing the distal ends thereof.Conductors connect the capacitor section terminals and the commonelement terminal to the distal ends of the respective terminal posts ofthe section cover terminals and common cover terminal. The conductorconnections at the distal ends of the terminal posts are broken uponoutward deformation of the cover. In more specific aspects, theconductors connecting the capacitor sections to the distal ends of thesection cover terminal posts are insulated wires, with the ends solderedto foil tabs that are welded or soldered to the distal ends of theterminal posts adjacent the disconnect plate.

Also, according to aspects of the invention herein, the common coverterminal is positioned generally centrally on the cover, and the sectioncover terminals are positioned at spaced apart locations surrounding thecommon cover terminal. The section cover terminals include at least oneblade connector, and preferably two or more blade connectors extendingoutwardly from the cover for receiving mating connectors for connectingselected ones of the capacitor sections into an electrical circuit. Thecommon cover terminal preferably has four blade connectors.

Additional aspects of the invention include providing means insulatingthe section and common cover terminals, the insulating means includingcylindrical cups upstanding from the cover, with the cylindrical cup ofat least the common cover terminal extending to or above the bladesthereof. According to a preferred aspect of the invention, theinsulation means includes a cover insulation barrier having a barriercup upstanding from the cover and substantially surrounding a centralcommon cover terminal and further having barrier fins radially extendingfrom the barrier cup and deployed between adjacent section coverterminals.

The invention herein is carried out by connecting one or more capacitorsections into an electrical circuit, by attaching leads to the coverterminals. This includes connecting capacitor sections in parallel,connecting capacitor sections in series, connecting individual capacitorsections, or connecting capacitor sections in combinations of paralleland series, as required to match the capacitance value or values of thefailed capacitor being replaced. The capacitor sections can be connectedto replace multiple capacitor values, as required, to substitute thecapacitor for the capacitor that has failed.

In another aspect of the invention, the capacitance values of thecapacitor sections are varied within a tolerance range from a statedvalue, such that one capacitor section may be utilized effectively toreplace one of two values, either individually or in combinations ofcapacitor sections.

Other and more specific objects and features of the invention hereinwill, in part, be understood by those skilled in the art and will, inpart, appear in the following description of the preferred embodiments,and claims, taken together with the drawings.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view of a capacitor according to the inventionherein;

FIG. 2 is a top view of the capacitor of FIG. 1;

FIG. 3 is a sectional view of the capacitor of FIG. 1, taken along thelines 3-3 of FIG. 2;

FIG. 4 is a side elevation view of the capacitive element of thecapacitor of FIG. 1, including wire conductors connected to thecapacitor sections thereof;

FIG. 5 is a top view of the capacitive element of the capacitor of FIG.1, including wire conductors connected to capacitor sections thereof;

FIG. 6 is an enlarged fragmentary plan view of a distal end of a wireconductor of FIGS. 4 and 5, connected to a foil tab;

FIG. 7 is an enlarged fragmentary side view of a distal end of a wireconductor of FIGS. 4 and 5, connected to a foil tab;

FIG. 8 is a sectional view of the capacitor of FIG. 1 taken along thelines 8-8 of FIG. 3, and showing a pressure interrupter cover assemblyof the capacitor of FIG. 1;

FIG. 9 is an exploded perspective view of the pressure interrupter coverassembly of the capacitor of FIG. 1;

FIG. 10 is an enlarged fragmentary view of the pressure interruptercover assembly of the capacitor of FIG. 1;

FIG. 11 is a top view of the capacitor of FIG. 1, shown with selectedcapacitor sections connected to a fan motor and a compressor motor;

FIG. 12 is a schematic circuit diagram of the capacitor of FIG. 1connected as shown in FIG. 11;

FIG. 13 is a top view of the capacitor of FIG. 1 with jumper wiresconnecting selected capacitor sections in parallel, and also shownconnected in an electrical circuit to a fan motor and a compressormotor;

FIG. 14 is a schematic circuit diagram of the capacitor of FIG. 1connected as shown in FIG. 13;

FIG. 15 is a top view of the capacitor of FIG. 1 connecting selectedcapacitor sections in series, and also shown connected in an electricalcircuit to a motor;

FIG. 16 is a schematic circuit diagram of the capacitor of FIG. 1 asconnected shown in FIG. 15;

FIG. 17 is a top view of the capacitor of FIG. 1 with a jumper wireconnecting selected capacitor sections in series, and also shownconnected in an electrical circuit to a compressor motor;

FIG. 18 is a schematic circuit diagram of the capacitor of FIG. 1connected as shown in FIG. 17;

FIG. 19 is a chart showing the single value capacitance values that maybe provided by the capacitor of FIG. 1;

FIG. 20 is a chart showing dual value capacitances that may be providedby the capacitor of FIG. 1;

FIG. 21 is another chart showing dual value capacitances that may beprovided by the capacitor of FIG. 1;

FIG. 22 is another chart showing dual value capacitances that may beprovided by the capacitor of FIG. 1;

FIG. 23 is another chart showing dual value capacitances that may beprovided by the capacitor of FIG. 1; and

FIG. 24 is a sectional view of the capacitor of FIG. 1, taken generallyalong the lines 24-24 of FIG. 2, but showing the capacitor after failureof the capacitive element.

The same reference numerals refer to the same elements throughout thevarious Figures.

DETAILED DESCRIPTION OF THE INVENTION

A capacitor 10 is shown in FIGS. 1-3, as well as in other Figures to bedescribed below. The capacitor 10 is adapted to replace any one of alarge number of capacitors. Therefore, a serviceman may carry acapacitor 10 on a service call and, upon encountering a failedcapacitor, the serviceman can utilize the capacitor 10 to replace thefailed capacitor with the capacitor 10 being connected to provide thesame capacitance value or values of the failed capacitor.

The capacitor 10 has a capacitive element 12 having a plurality ofcapacitor sections, each having a capacitance value. The capacitiveelement 12 is also shown in FIGS. 4 and 5. In the preferred embodimentdescribed herein, the capacitive element 12 has six capacitor sections20-25. The capacitive element 12 is a wound cylindrical elementmanufactured by extension of the techniques described in my prior U.S.Pat. No. 3,921,041, my U.S. Pat. No. 4,028,595, my U.S. Pat. No.4,352,145 and my U.S. Pat. No. 5,313,360, incorporated herein byreference. Those patents relate to capacitive elements having twocapacitor sections rather than a larger plurality of capacitor sections,such as the six capacitor sections 20-25 of the capacitive element 12.Accordingly, the capacitive element 12 has a central spool or mandrel28, which has a central opening 29. First and second dielectric films,each having a metalized layer on one side thereof, are wound incylindrical form on the mandrel 28 with the nonmetalized side of onefilm being in contact with the metalized side of the other. Selectedportions of one or both of the metalized layers are removed in order toprovide a multiple section capacitor. Element insulation barriers areinserted into the winding to separate the capacitor sections, theelement insulation barriers also assuming a cylindrical configuration.Five element insulation barriers 30-34 are provided to separate the sixcapacitor sections 20-25, with element insulation barrier 30 separatingcapacitor sections 20 and 21, element insulation barrier 31 separatingcapacitor sections 21 and 22, element insulation barrier 32 separatingcapacitor sections 22 and 23, element insulation barrier 33 separatingcapacitor sections 23 and 24, and element insulation barrier 34separating capacitor sections 24 and 25.

The element insulation barriers are insulating polymer sheet material,which in the capacitive element 12 is polypropylene having a thicknessof 0.005 inches, wound into the capacitive element 12. Thickness of0.0025 to 0.007 may be used. Other materials may also be used. Thebarriers each have about 2%-4 wraps of the polypropylene sheet material,wherein the element insulation barriers have a thickness of about 0.013to 0.020 inches. The barriers 30-34 are thicker than used before incapacitors with fewer capacitor sections. The important characteristicof the barriers 30-34 is that they are able to withstand heat fromadjacent soldering without losing integrity of electrical insulation,such that adjacent sections can become bridged.

As is known in the art, the metalized films each have one unmetalizedmarginal edge, such that the metalized marginal edge of one film isexposed at one end of the wound capacitive element 12 and the metalizedmarginal edge of the other film is exposed at the other end of thecapacitive element 12. With reference to FIGS. 3 and 5, at the lower endof the capacitance element 12, the barriers 30-34 do not extend from thefilm, and an element common terminal 36 is established contacting theexposed metalized marginal edges of one metalized film of all thecapacitor sections 20-25. The element common terminal 36 is preferably azinc spray applied onto the end of the capacitive element 12.

At the top end of the capacitive element 12 as depicted in FIGS. 3 and5, the element insulation barriers 30-34 extend above the woundmetalized film. An individual capacitor element section terminal isprovided for each of the capacitive sections 20-25, also by applying azinc or other metallic spray onto the end of the capacitive element 12with the zinc being deployed on each of the capacitor sections 20-25between and adjacent the element insulation barriers 30-34. The elementsection terminals are identified by numerals 40-45. Element sectionterminal 40 of capacitor section 20 extends from the outer-most elementinsulation barrier 30 to the outer surface of the capacitive element 12,and the element section terminal 45 of capacitor section 25 extends fromthe inner-most element insulation barrier 34 to the central mandrel 28.Element section terminals 41-44 are respectively deployed on thecapacitor sections 21-24.

Conductors preferably in the form of six insulated wires 50-55 each haveone of their ends respectively soldered to the element section terminals40-45, as best seen in FIG. 5. The thickness of the polypropylenebarriers 30-34 resists any burn-through as a result of the soldering toconnect wires 50-55 to the terminals 40-45.

The insulation of the wires 50-55 is color coded to facilitateidentifying which wire is connected to which capacitor section. Wire 50connected to element section terminal 40 of capacitor section 20 hasblue insulation, wire 51 connected to element section terminal 41 ofcapacitor section 21 has yellow insulation, wire 52 connected to elementsection terminal 42 of capacitor section 22 has red insulation, wire 53connected to element section terminal 43 of capacitor section 23 haswhite insulation, wire 54 connection to element section terminal 44 ofcapacitor section 24 has white insulation, and wire 55 connected toelement section terminal 45 of capacitor section 25 has greeninsulation. These colors are indicated on FIG. 4.

The capacitive element 12 is further provided with foil strip conductor38, having one end attached to the element common terminal 36 at 37. Thefoil strip conductor 38 is coated with insulation, except for the pointof attachment 37 and the distal end 39 thereof. The conductor 50connected to the outer capacitor element section 20 and its terminal 30may also be a foil strip conductor. If desired, foil or wire conductorsmay be utilized for all connections.

In the capacitive element 12 used in the capacitor 10, the capacitorsection 20 has a value of 25.0 microfarads and the capacitor section 21has a capacitance of 20.0 microfarads. The capacitor section 22 has acapacitance of 10.0 microfarads. The capacitor section 23 has acapacitance of 5.5 microfarads, but is identified as having acapacitance of 5.0 microfarads for purposes further discussed below. Thecapacitor section 24 has a capacitance of 4.5 microfarads but is labeledas having a capacitance of 5 microfarads, again for purposes describedbelow. The capacitor section 25 has a capacitance of 2.8 microfarads.The capacitor section 20 with the largest capacitance value also has themost metallic film, and is therefore advantageously located at the outersection or at least one of the three outer sections of the capacitiveelement 12.

The capacitor 10 also has a case 60, best seen in FIGS. 1-3, having acylindrical side wall 62, a bottom wall 64, and an open top 66 of sidewall 62. The case 60 is formed of aluminum and the cylindrical side wall62 has an outside diameter of 2.50 inches. This is a very commondiameter for capacitors of this type, wherein the capacitor 10 will bereadily received in the mounting space and with the mounting hardwareprovided for the capacitor being replaced. Other diameters may, however,be used, and the case may also be plastic or of other suitable material.

The capacitive element 12 with the wires 50-55 and the foil strip 38 arereceived in the case 60 with the element common terminal 36 adjacent thebottom wall 64 of the case. An insulating bottom cup 70 is preferablyprovided for insulating the capacitive element from the bottom wall 64,the bottom cup 70 having a center post 72 that is received in the centeropening 29 of the mandrel 28, and an up-turned skirt 74 that embracesthe lower side wall of the cylindrical capacitive element 12 and spacesit from the side wall 62 of the case 60.

An insulating fluid 76 is provided within the case 60, at least partlyand preferably substantially surrounding the capacitive element 12. Thefluid 76 may be the fluid described in my U.S. Pat. No. 6,014,308,incorporated herein by reference, or one of the other insulating fluidsused in the trade, such as polybutene.

The capacitor 10 also has a pressure interrupter cover assembly 80 bestseen in FIGS. 1-3, 8-10 and 24. The cover assembly 80 includes adeformable circular cover 82 having an upstanding cylindrical skirt 84and a peripheral rim 86 as best seen in FIGS. 9 and 10. The skirt 84fits into the open top 66 cylindrical side wall 62 of case 60, and theperipheral rim 86 is crimped to the open top 66 of the case 60 to sealthe interior of the capacitor 10 and the fluid 76 contained therein, asshown in FIGS. 1 and 3.

The pressure interrupter cover assembly 80 includes seven coverterminals mounted on the deformable cover 82. A common cover terminal 88is mounted generally centrally on the cover 82, and section coverterminals 90-95, each respectively corresponding to one of the capacitorsections 20-25, are mounted at spaced apart locations surrounding thecommon cover terminal 88. With particular reference to FIGS. 1, 2, 9 and10, the section cover terminal 91 has three upstanding blades 98, 100and 102 mounted on the upper end of a terminal post 104. Terminal post104 has a distal end 105, opposite the blades 98, 100 and 102. The cover82 has an opening 106 for accommodating the terminal post 104, and has abeveled lip 107 surrounding the opening. A shaped silicone insulator 108fits snuggly under the cover in the beveled lip 107 and the terminalpost 104 passes through the insulator 108. On the upper side of thecover, an insulator cup 110 also surrounds the post 104, and theinsulator cup 110 sits atop the silicone insulator 108; thus, theterminal 91 and its terminal post 104 are well insulated from the cover82. The other cover section terminals 92-95 are similarly mounted withan insulator cup and a silicone insulator.

The common cover terminal 88 has four blades 120, and a terminal post122 that passes through a silicone insulator 112. The common coverterminal 88 mounts cover insulator barrier 114 that includes anelongated cylindrical center barrier cup 116 surrounding and extendingabove the blades 120 of the cover common terminal 88, and six barrierfins 118 that extend respectively radially outwardly from the elongatedcenter barrier cup 116 such that they are deployed between adjacentsection cover terminals 90-95. This provides additional protectionagainst any arcing or bridging contact between adjacent section coverterminals or with the common cover terminal 88. Alternatively, thecommon cover terminal 88 may be provided with an insulator cup 116,preferably extending above blades 120 but with no separating barrierfins, although the barrier fins 118 are preferred. The terminal post 122extends through an opening in the bottom of the base 117 of theinsulating barrier cup 116, and through the silicone insulator 112, to adistal end 124.

The pressure interrupter cover assembly 80 has a fiberboard disc 126through which the terminal posts 122, terminal post 104 and the terminalposts of the other section cover terminals extend. The disc 126 may bealso fabricated of other suitable material, such as polymers. Theterminal posts 104, 122, etc. are configured as rivets with rivetflanges 128 for assembly purposes. The terminal posts 104, 122, etc. areinserted through the disc 126, insulators 108, 112, insulator cups 110and barrier cup 116, and the cover terminals 88, 90-95 are spot weldedto the ends of the rivets opposite the rivet flanges 128. Thus, therivet flanges 128 secure the cover terminals 88, 90-95 in the cover 82,together with the insulator barrier 114, insulator cups 110 and siliconeinsulators 108, 112. The fiberboard disc 126 facilitates this assembly,but may be omitted, if desired. The distal ends of the terminal postsare preferably exposed below the rivet flanges 128.

The cover assembly 80 has a disconnect plate 130, perhaps best seen inFIGS. 3, 9 and 10. The disconnect plate 130 is made of a rigidinsulating material, such as a phenolic, is spaced below the cover 82 bya spacer 134 in the form of a skirt. The disconnect plate 130 isprovided with openings accommodating the distal ends of the terminalposts, such as opening 136 accommodating the distal end 105 of terminalpost 104 and opening 138 accommodating the distal end 124 of theterminal post 122. With particular reference to FIG. 9, the disconnectplate 130 may be provided with raised guides, such as linear guides 140and dimple guides 142, generally adjacent the openings accommodating thedistal ends of terminal posts. These guides are for positioning purposesas discussed below.

In prior capacitors having three or fewer capacitor sections, theconductors between the capacitor sections and the terminal posts weregenerally foil strips, such as the one used for the common terminal 36of the capacitive element 12 herein. The foil strips were positioned ona breaker plate over the distal ends of terminal posts, and were weldedto the distal ends of the terminal posts. In capacitor 10, the distalend 39 of the foil strip 38 is connected to the distal end 124 ofterminal post 122 by welding, as in prior capacitors.

The wires 50-55 are not well-configured for welding to the distal endsof the terminal posts of the cover section terminals. However, the wires50-55 are desirable in place of foil strips because they are betteraccommodated in the case 60 and have good insulating properties, resistnicking and are readily available with colored insulations. In order tomake the necessary connection of the wires 50-55 to their respectiveterminal posts, foil tabs 56 are welded to each of the distal ends ofthe terminal posts of the section cover terminals 90-95, and the guides140, 142 are helpful in positioning the foil tabs 56 for the weldingprocedure. The attachment may be accomplished by welding the distal endof a foil strip to the terminal post, and then cutting the foil strip toleave the foil tab 56. Thereafter, and as best seen in FIGS. 6, 7 and10, the conductor 58 of wire 50 is soldered to the tab 56, by solder 57.The insulation 59 of wire 50 has been stripped to expose the conductor58. The other wires 51-55 are similarly connected to their respectivecover section terminals. Alternatively, the foil tabs may be soldered tothe wires and the tabs may then be welded to the terminal posts, ifdesired, or other conductive attachment may be employed.

Accordingly, each of the capacitor sections 20-25 is connected to acorresponding section cover terminal 90-95 by a respective one of colorcoded wires 50-55. The insulator cups 110 associated with each of thesection cover terminals 90-95 are also color coded, using the same colorscheme as used in the wires 50-55. This facilitates assembly, in thateach capacitor section and its wire conductor are readily associatedwith the correct corresponding section cover terminal, so that thecorrect capacitor sections can be identified on the cover to make thedesired connections for establishing a selected capacitance value.

The connections of the wires 50-55 and the foil 38 to the terminal postsis made prior to placing the capacitive element 12 in the case 60,adding the insulating fluid 76, and sealing the cover 82 of coverassembly 80 to the case 60. The case 60 may be labeled with thecapacitance values of the capacitance sections 20-25 adjacent the coverterminals, such as on the side of case 60 near the cover 82 or on thecover 82.

The capacitor 10 may be used to replace a failed capacitor of any one ofover two hundred different capacitance values, including both single anddual applications. Therefore, a serviceman is able to replace virtuallyany failed capacitor he may encounter as he makes service calls onequipment of various manufacturers, models, ages and the like.

As noted above, the capacitor 10 is expected to be used most widely inservicing air conditioning units. Air conditioning units typically havetwo capacitors; a capacitor for the compressor motor which may or maynot be of relatively high capacitance value and a capacitor ofrelatively low capacitance value for a fan motor. The compressor motorcapacitors typically have capacitances of from 20 to about 60microfarads. The fan motor capacitors typically have capacitance valuesfrom about 2.5 to 12.5 microfarads, and sometimes as high as 15microfarads, although values at the lower end of the range are mostcommon.

With reference to FIG. 11, capacitor 10 is connected to replace acompressor motor capacitor and a fan motor capacitor, where thecompressor motor capacitor has a value of 25.0 microfarads and the fanmotor capacitor has a value of 4.0 microfarads. The 25.0 microfaradreplacement capacitance for the compressor motor is made by one of thecompressor motor leads 160 being connected to one of the blades of theblue section cover terminal 90 of capacitance section 20, which has acapacitance value of 25.0 microfarads, and the other compressor motorlead 161 being connected to one of the blades 120 of common coverterminal 88. The lead 162 from the fan motor is connected to the whitesection cover terminal 94 of capacitor section 24, and the second lead163 from the fan motor is also connected to the common cover terminal88. As set forth above, the actual capacitance value of the capacitorsection 24 that is connected to the section cover terminal 94 is 4.5microfarads, and the instructions and/or labeling for the capacitor 10indicate that the capacitor section 24 as represented at terminal 94should be used for a 4.0 microfarad replacement. Preferred labeling forthis purpose can be “5.0 (4.0) microfarads” or similar. The 4.5microfarad capacitance value is within approximately 10% of thespecified 4.0 microfarad value, and that is within acceptable tolerancesfor proper operation of the fan motor. Of course, the capacitor section24 and terminal 94 may be connected to replace a 5.0 microfaradcapacitance value as well, whereby the 4.5 microfarad actual capacitancevalue of capacitor section 24 gives added flexibility in replacingfailed capacitors. Similarly, the 5.5 microfarad capacitor section 23can be used for either 5.0 microfarad or 6.0 microfarad replacement, andthe 2.8 microfarad section 25 can be used for a 3.0 microfaradreplacement or for a 2.5 microfarad additive value. FIG. 12schematically illustrates the connection of capacitor sections 20 and 24to the compressor motor and fan motor shown in FIG. 11.

FIG. 13 illustrates another connection of the capacitor 10 for replacinga 60.0 microfarad compressor motor capacitor and a 7.5 microfarad fanmotor capacitor. The formula for the total capacitance value forcapacitors connected in parallel is additive namely: C_(t)=C₁+C₂+C₃ . .. . Therefore, with reference to FIG. 13, a 60.0 microfarad capacitancevalue for the compressor motor is achieved by connecting in parallel thesection cover terminal 90 (capacitor section 20 at a value of 25.0microfarads), section cover terminal 91 (capacitor section 21 at a valueof 20.0 microfarads), section cover terminal 92 (capacitor section 22 ata value of 10.0 microfarads) and section cover terminal 93 (capacitorsection 23 at a nominal value of 5.0 microfarads). The foregoingconnections are made by means of jumpers 164, 165 and 166, which may besupplied with the capacitor 10. Lead 167 is connected from the sectioncover terminal 90 of the capacitor section 20 to the compressor motor,and lead 168 is connected from the common cover terminal 88 to thecompressor motor. This has the effect of connecting the specifiedcapacitor sections 20, 21, 22 and 23 in parallel, giving a total of 60.0microfarad capacitance; to wit: 25+20+10+5=60. It is preferred but notrequired to connect the lead from the compressor motor or the fan motorto the highest value capacitor section used in providing the totalcapacitance.

Similarly, a 7.5 microfarad capacitance is provided to the fan motor byconnecting section cover terminal 94 of the 5.0 microfarad capacitorsection 24 and the section cover terminal 95 of the nominal 2.5microfarad capacitor section 25 in parallel via jumper 169. Leads 170and 171 connect the fan motor to the common cover terminal 88 and thesection cover terminal 95 of the capacitor section 25. FIG. 14diagrammatically illustrates the connection of the capacitor 10 shown inFIG. 13.

It will be appreciated that various other jumper connections betweensection cover terminals can be utilized to connect selected capacitorsections in parallel, in order to provide a wide variety of capacitancereplacement values.

The capacitor sections can also be connected in series to utilizecapacitor 10 as a single value replacement capacitor. This has the addedadvantage of increasing the voltage rating of the capacitor 10 in aseries application, i.e. the capacitor 10 can safely operate at highervoltages when its sections are connected in series. As a practicalmatter, the operating voltage will not be increased as it is establishedby the existing equipment and circuit, and the increased voltage ratingderived from a series connection will increase the life of the capacitor10 because it will be operating well below its maximum rating.

With reference to FIG. 15, the capacitor 10 is shown with capacitorsection 22 (terminal 92) having a value of 10.0 microfarads connected inseries with capacitor section 25 (terminal 95) having a nominal value of2.5 microfarads to provide a replacement capacitance value of 2.0microfarads. Leads 175 and 176 make the connections from the respectivesection cover terminals 92 and 95 to the motor, and the element commonterminal 36 connects the capacitor sections 22 and 25 of capacitiveelement 12. With reference to FIG. 16, the connection of capacitor 10shown in FIG. 15 is illustrated diagrammatically. In both FIGS. 15 and16, it will be seen that the cover common terminal 88 is not used inmaking series connections.

The formula for capacitance of capacitors connected in series is:

$\frac{1}{C_{T}} = {\frac{1}{C_{1}} + \frac{1}{C_{2}} + {\frac{1}{C_{3}}\ldots}}$

Therefore,

${C_{T} = \frac{C_{1} \times C_{2}}{C_{1} + C_{2}}},$

and the total capacitance of the capacitor sections 22 and 25 connectedas shown in FIGS. 15 and 16 is

$C_{T} = {\frac{10.0 \times 2.5}{10.0 + 2.5} = {\frac{25}{12.5} = {2.0\mspace{14mu}{{microfarads}.}}}}$

The capacitance of each of the capacitor sections 20-25 is rated at 440volts. However, when two or more capacitor sections 20-25 are connectedin series, the applied voltage section is divided between the capacitorsections in inverse proportion to their value. Thus, in the seriesconnection of FIGS. 15 and 16, the nominal 2.5 microfarad section seesabout 80% of the applied voltage and the 10.0 microfarad section seesabout 20% of the applied voltage. The net effect is that the capacitor10 provides the 2.0 microfarad replacement value at a higher rating, dueto the series connection. In this configuration, the capacitor 10 islightly stressed and is apt to have an extremely long life.

With reference to FIG. 17, the capacitor sections of the capacitor 10are shown connected in a combination of parallel and series connectionsto provide additional capacitive values at high voltage ratings, in thiscase 5.0 microfarads. The two capacitor sections 23 and 24 each having anominal value of 5.0 microfarads are connected in parallel by jumper 177between their respective cover section terminals 93 and 94. The leads178 and 179 from a compressor motor are connected to the section coverterminal 92 of capacitor section 22 having a value of 10.0 microfarads,and the other lead is connected to cover section terminal 94 ofcapacitor section 24. Thus, a capacitance value of 5.0 microfarads isprovided according to the following

$\frac{1}{C_{T}} = {\frac{1}{C_{1}} + \frac{1}{C_{2}}}$

where C₁ is a parallel connection having the value C+C, in this case5.0+5.0 for a C₁ of 10.0 microfarads. With that substitution, the totalvalue is

$C_{T} = {\frac{10.0 \times 10.0}{10 + 10} = {\frac{100}{20} = {5.0\mspace{14mu}{{microfarads}.}}}}$

The connection of capacitor 10 illustrated in FIG. 17 is showndiagrammatically in FIG. 18.

FIG. 19 is a chart showing single capacitance values that can beprovided by the capacitor 10 connected in parallel. The values arederived by connecting individual capacitor sections into a circuit, orby parallel connections of capacitor sections. The chart should beinterpreted remembering that the 2.8 microfarad capacitor section can beused as a 2.5 or 3.0 microfarad replacement, and that the two 5.0microfarad values are actually 4.5 and 5.5 microfarad capacitorsections, also with possibilities for more replacements.

FIGS. 20-23 are charts showing applications of capacitor 10 in replacingboth a fan motor capacitor and a compressor motor capacitor. This is animportant capability, because many air conditioning systems are equippedwith dual value capacitors and when one of the values fails, anotherdual value capacitor must be substituted into the mounting spacebracket.

The chart of FIG. 20 shows dual value capacitances that can be providedby capacitor 10 wherein the nominal 2.5 microfarad capacitor section 25is used for one of the dual values, usually the fan motor. Fan motorsare generally not rigid in their requirements for an exact capacitancevalue, wherein the capacitor section 25 may also be used for fan motorsspecifying a 3.0 microfarad capacitor. The remaining capacitor sections20-24 are available for connection individually or in parallel to thecompressor motor, providing capacitance values from 5.0 to 65.0microfarads in 5.0 microfarad increments.

The chart of FIG. 21 also shows dual value capacitances that can beprovided by capacitor 10. In the chart of FIG. 21, one of the dualvalues is 5.0 microfarads that can be provided by either capacitorsection 23 having an actual capacitance value of 5.5 microfarads or bycapacitor section 24 having an actual capacitance of 4.5 microfarads. Asdiscussed above, the capacitor section 24 can also be used for a 4.0microfarad replacement value, and capacitor section 23 could be used fora 6.0 microfarad replacement value. Thus, chart 21 represents more dualreplacement values than are specifically listed. The other capacitorsection may be used in various parallel connections to achieve thesecond of the dual capacitance values.

Chart 22 illustrates yet additional dual value capacitances that can beprovided by capacitor 10. Capacitor section 25 (nominal 2.5 microfarads)is connected in parallel with one of capacitor section 23 (5.5microfarads) or capacitor section 24 (4.5 microfarads) to provide a 7.5microfarad capacitance value as one of the dual value capacitances. Theremaining capacitor sections are used individually or in parallel toprovide the second of the dual value capacitances.

Chart 23 illustrates yet additional dual value capacitances that can beprovided by capacitor 10, where capacitor section 22 (10 microfarads) isdedicated to provide one of the dual values. The remaining capacitorsections are used individually or in parallel for the other of the dualvalues.

It will be appreciated that any one or group of capacitor sections maybe used for one of a dual value, with a selected one or group of theremaining capacitor sections connected to provide another capacitancevalue. Although there are no known applications, it will also beappreciated that the capacitor 10 could provide six individualcapacitance values corresponding to the capacitor sections, or three,four or five capacitance values in selected individual and parallelconnections. Additional single values can be derived from seriesconnections.

The six capacitor sections 20-25 can provide hundreds of replacementvalues, including single and dual values. It will further be appreciatedthat if fewer replacement values are required, the capacitor 10 can bemade with five or even four capacitor sections, and that if morereplacement values were desired, the capacitor 10 could be made withmore than six capacitor sections. It is believed that, at least in theintended field of use for replacement of air conditioner capacitors,there should be a minimum of five capacitor sections and preferably sixcapacitor sections to provide an adequate number of replacement values.

As is known in the art, there are occasional failures of capacitiveelements made of wound metalized polymer film. If the capacitive elementfails, it may do so in a sudden and violent manner, producing heat andoutgassing such that high internal pressures are developed within thehousing. Pressure responsive interrupter systems have been designed tobreak the connection between the capacitive element and the coverterminals in response to the high internal pressure, thereby removingthe capacitive element from a circuit and stopping the high heat andoverpressure condition within the housing before the housing ruptures.Such pressure interrupter systems have been provided for capacitorshaving two and three cover terminals, including the common terminal, butit has not been known to provide a capacitor with five or more capacitorsections and a pressure interrupter cover assembly.

The pressure interrupter cover assembly 80 provides such protection forthe capacitor 10 and its capacitive element 12. With reference to FIG.24, the capacitor 10 is shown after failure. Outgassing has caused thecircular cover 82 to deform upwardly into a generally domed shape. Whenthe cover 82 deforms in the manner shown, the terminal posts are alsodisplaced upwardly from the disconnect plate 130, and the weldconnection of the distal end 124 of common cover terminal post 122 tothe distal end 39 foil lead 38 from the common element 36 of thecapacitive element 12 is broken, and the welds between the foil tabs 56and the terminal posts 104 of the section cover terminals 90-95 are alsobroken, the separation at section cover terminals 91 and 94 being shown.

Although the preferred pressure interrupter cover assembly includes thefoil lead 38 and foil tabs 56, frangibly connected to the distal ends ofthe terminal posts, the frangible connections both known in the art andto be developed may be used. As an example, the terminal poststhemselves may be frangible.

It should be noted that although it is desirable that the connections ofthe capacitive element and all cover terminals break, it is notnecessary that they all do so in order to disconnect the capacitiveelement 12 from a circuit. For all instances in which the capacitor 10is used with its capacitor sections connected individually or inparallel, only the terminal post 122 of common cover terminal 88 must bedisconnected in order to remove the capacitive element 12 from thecircuit. Locating the cover common terminal 88 in the center of thecover 82, where the deformation of the cover 82 is the greatest, ensuresthat the common cover terminal connection is broken both first and withcertainty in the event of a failure of the capacitive element 12.

If the capacitor sections of the capacitor 10 are utilized in a seriesconnection, it is necessary that only one of the terminal posts used inthe series connection be disconnected from its foil tab at thedisconnect plate 130 to remove the capacitive element from an electricalcircuit. In this regard, it should be noted that the outgassingcondition will persist until the pressure interrupter cover assembly 80deforms sufficiently to cause disconnection from the circuit, and it isbelieved that an incremental amount of outgassing may occur as requiredto cause sufficient deformation and breakage of the circuit connectionat the terminal post of one of the section cover terminal. However, inthe most common applications of the capacitor 10, the common coverterminal 88 will be used and the central location of the common coverterminal 88 will cause fast and certain disconnect upon any failure ofthe capacitive element.

Two other aspects of the design are pertinent to the performance of thepressure interrupter system. First, with respect to series connectionsonly, the common cover terminal 88 may be twisted to pre-break theconnection of the terminal post 122 with the foil strip 38, thuseliminating the requirement of any force to break that connection in theevent of a failure of the capacitive element 12. The force that wouldotherwise be required to break the connection of common terminal post122 is then applied to the terminal posts of the section coverterminals, whereby the section cover terminals are more readilydisconnected. This makes the pressure interrupter cover assembly 80highly responsive in a series connection configuration.

Second, the structural aspects of welding foil tabs to the distal endsof the terminal posts corresponding to the various capacitor sectionsand thereafter soldering the connecting wires onto the foil tabs 56 isalso believed to make the pressure interrupter cover assembly 80 moreresponsive to failure of the capacitive element 12. In particular, thesolder and wire greatly enhance the rigidity of the foil tabs 56 whereinupon deformation of the cover 82, the terminal posts break cleanly fromthe foil tabs 56 instead of pulling the foil tabs partially through thedisconnect plate before separating. Thus, the capacitor 10, despitehaving a common cover terminal and section cover terminals for sixcapacitor sections, is able to satisfy safety requirements forfluid-filled metalized film capacitors, which is considered asubstantial advance in the art.

The capacitor 10 and the features thereof described above are believedto admirably achieve the objects of the invention and to provide apractical and valuable advance in the art by facilitating efficientreplacement of failed capacitors. Those skilled in the art willappreciate that the foregoing description is illustrative and thatvarious modifications may be made without departing from the spirit andscope of the invention, which is defined in the following claims.

What is claimed is:
 1. An apparatus suitable for use in an air-conditioning system and configured to provide a plurality of selectable capacitance values, comprising: a plurality of capacitive devices housed in a case, each of the capacitive devices having a first capacitor terminal and a second capacitor terminal, three of the capacitive devices having a combined capacitance value of about 55.0 microfarads; a pressure interrupter cover assembly comprising: a deformable cover mountable to the case, a set of capacitor cover terminals, each capacitor cover terminal having at least one contact extending from the deformable cover, wherein the deformable cover is configured to displace at least one of the capacitor cover terminals based upon an operative failure, a common cover terminal having at least one contact extending from the deformable cover, and a set of insulation structures, wherein each insulation structure is configured to provide insulation for at least one of the capacitor cover terminals; and a conductor configured to electrically connect the second capacitor terminal of at least one of the capacitive devices to the common cover terminal, wherein the first capacitor terminal of the at least one of the capacitive devices is electrically connected to one of the capacitor cover terminals.
 2. The apparatus of claim 1, each of the plurality of capacitive devices being provided by a section of a wound capacitive element.
 3. The apparatus of claim 1, the apparatus being configured for use by a compressor motor of the air-conditioning system and for use by a fan motor of the air-conditioning system.
 4. The apparatus of claim 1, wherein the apparatus comprises six capacitive devices.
 5. The apparatus of claim 4, wherein at least one of the insulation structures is cup shaped.
 6. The apparatus of claim 4, wherein four of the capacitive devices have a combined capacitance value greater than about 60.0 microfarads and two of the capacitive devices have a combined capacitance value greater than about 6.0 microfarads.
 7. The apparatus of claim 1, wherein at least one of the capacitor cover terminals includes at least two blades.
 8. The apparatus of claim 1, wherein the common cover terminal includes at least two blades.
 9. The apparatus of claim 1, wherein at least one of the insulation structures includes an insulator cup.
 10. The apparatus of claim 1, each of the plurality of capacitive devices being sections of a wound capacitive element.
 11. An apparatus suitable for use in an air-conditioning system and configured to provide a plurality of selectable capacitance values, comprising: a plurality of capacitive devices housed in a case, each of the capacitive devices having a first capacitor terminal and a second capacitor terminal, three of the capacitive devices having a combined capacitance value of about 55.0 microfarads; and a pressure interrupter cover assembly comprising: a deformable cover mountable to the case, a set of capacitor cover terminals, each capacitor cover terminal having at least one contact extending from the deformable cover, wherein the deformable cover is configured to displace at least one of the capacitor cover terminals based upon an operative failure, a common cover terminal having at least one contact extending from the deformable cover, and a set of insulation structures, wherein each insulation structure is configured to provide insulation for at least one of the capacitor cover terminals, wherein the first capacitor terminal of at least one of the capacitive devices is electrically connectable to one of the capacitor cover terminals, and wherein the second capacitor terminal of the at least one of the capacitive devices is electrically connectable to the common cover terminal.
 12. The apparatus of claim 11, each of the plurality of capacitive devices being provided by a section of a wound capacitive element.
 13. The apparatus of claim 11, the apparatus being configured for use by a compressor motor of the air-conditioning system and for use by a fan motor of the air-conditioning system.
 14. The apparatus of claim 11, wherein the apparatus comprises six capacitive devices.
 15. The apparatus of claim 14, wherein at least one of the insulation structures is cup shaped.
 16. The apparatus of claim 14, wherein four of the capacitive devices have a combined capacitance value greater than about 60.0 microfarads and two of the capacitive devices have a combined capacitance value greater than about 6.0 microfarads.
 17. The apparatus of claim 11, wherein at least one of the capacitor cover terminals includes at least two blades.
 18. The apparatus of claim 11, wherein the common cover terminal includes at least two blades.
 19. The apparatus of claim 11, wherein at least one of the insulation structures includes an insulator cup.
 20. The apparatus of claim 11, each of the plurality of capacitive devices being sections of a wound capacitive element. 